Phosphonated cyclic mercaptal

ABSTRACT

PHOSPHONATED CYCLIC MERCAPTALS AND MERCAPTOLES CORRESPONDING TO THE FORMULA   R1-O-P(=X)(-R)-S-ALKYLENE-C(-R2)&lt;(-X-CH2-(CH2)N-X-)   IN WHICH ALKYLENE IS A DIVALENT SATURATED ALIPHATIC RADICAL HAVING FROM 1 TO 3 CARBON ATOMS; R AND R1 ARE LOWER ALKYL AND PHENYL; THE GROUPS REPRESENTED BY X ARE INDEPENDENTLY SULFUR OR OXYGEN; R2 IS AN ALKYL FROM 1 TO 3 CARBONS OR HYDROGEN AND N IS AN INTEGER FROM 1 TO 2, INCLUSIVE. THE ABOVE COMPOUNDS ARE EFFECTIE INSECTICIDES AND MITICIDES. REPRESENTATIVE COMPOUNDS ARE 2-METHYL-2(O-ETHYL ETHYLPHOSPHORODITHIOMETHYLENE)-1,3-OXATHIOLANE, DITHIOLANE, 2-METHYL-2-(O-ETHYL METHYLPHOSPHORODITHIOMETHYLENE)-1,3-DITHIOLANE, AND 2-METHYL-2-(O-ETHYLPHENYLPHOSPHONODITHIOMETHYLENE)-1,3-DITHIOLANE.

United States Patent Oflice 3,564,013 PHOSPHONATED CYCLIC MERCAPTAL Edward Nelson Walsh, Chicago Heights, Ill., assignor to Stautfer Chemical Company, New York, N.Y., a corporation of Delaware No Drawing. Filed July 9, 1964, Ser. No. 381,509 The portion of the term of the patent subsequent to Feb. 16, 1986, has been disclaimed and dedicated to the Public Int. Cl. C07d 89/06 US. Cl. 260-327 1 Claim ABSTRACT OF THE DISCLOSURE Phosphonated cyclic mercaptals and mercaptoles corresponding to the formula in which alkylene is a divalent saturated aliphatic radical having from 1 to 3 carbon atoms; R and R are lower alkyl and phenyl; the groups represented by X are independently sulfur or oxygen; R is an alkyl from 1 to 3 carbons or hydrogen and n is an integer from 1 to 2, inelusive. The above compounds are eifective insecticides and miticides. Representative compounds are 2-methyl-2- (O-ethyl ethylphosphorodithiomethylene)-1,3-oxathiolane, 2-methyl-2-(O-ethyl ethylphosphorodithiomethylene) 1,3- dithiolane, Z-methyl-Z-(O-ethyl methylphosphorodithiomethylene)-1,3-dithiolane, and 2'-methyl-2-(O-ethylphenylphosphonodithiomethylene)-1,3-dithiolane.

The present invention is concerned with a novel group of phosphonated cyclic mercaptals, their method of preparation, and use as pesticides. Also the invention is concerned with the novel intermediates from which these pesticides are manufactured and a method of preparing the same.

The novel pesticides may be represented by the general formula wherein alkylene means a divalent saturated aliphatic radical having from 1 to 3 carbon atoms; R and R are selected from the group consisting of lower alkyl and phenyl; the groups represented by X are independently selected from the group consisting of sulfur and oxygen; R is an alkyl from 1 to 3 carbons or hydrogen and n is an integer of from 1 to 2, inclusive. The lower alkyl radicals which are suitable for R and R are the straight and branched chain aliphatic radicals having from 1 to 8 carbon atoms and include for example, methyl, ethyl, propyl, isopropyl, amyl, octyl, and the like. The lower alkyl radicals which are suitable for R are the straight and branched chain aliphatic radicals having from 1 to 3 carbon atoms and include for example, methyl, ethyl, propyl, and isopropyl.

The general process for preparing the novel pesticides Patented Feb. 16, 1971 of the invention may be illustrated by the following reaction:

wherein R, R, R X, n, and alkylene are the same as defined above. The reaction is preferably carried out in the presence of a strong acid catalyst such as boron trifluoride etherate or gaseous HCl; an inert organic solvent such as ethyl ether, benzene, and the like may be used, but is not required. Reaction temperatures during these exothermic reactions are generally maintained between 0 C. and C., and a preferred temperature range is between 20 C. and 50 C. Higher temperatures may cause appreciable side products to form due to an attack by the acid catalyst. In the preferred process, the mercaptans are added to the phosphonated aldehyde or ketone reactant before addition of the catalyst. Although the order of addition may have some slight effects on yields, it is not a critical feature of the invention.

Recovery of a pure phosphonated cyclic mercaptal from the reaction mixture may be accomplished by washing the reaction mixture to remove side products, unreacted compounds, and the acid catalyst. For convenience, the reaction mixture may first be dissolved in an inert organic solvent such as benzene, ether, and the like, and then washed. The washing may be accomplished with water or aqueous solutions of sodium bicarbonate, sodium sulfate, etc. (to remove the unreacted aldehyde or ketone). Normally the reaction will yield 'between 71% and 97% of the theoretical predicated amount of phosphonated cyclic mercaptal.

The following examples illustrate specific pesticides of the invention and their method of preparation, but should not be construed as limiting the broader aspects of the To 6.0 grams of tczH (C2H5O)P(S)SCH2C(O) (CH3) contained in a reactor flask fitted with a stirrer and thermometer was added 2.5 grams of ethandithiol. The reactants were dissolved in 5 ml. of ethyl ether and 0.5 ml. of boron trifiuoride etherate was added to catalyze the reaction. A mild exothermic reaction ensued; the temperature was held at 30 C. to 35 C. After stirring for 16 hours, 100 ml. of ethyl ether was added, and the reactants were washed with 100 cc. of water. The reactants were counterwashed with 50 cc. of ethyl ether and 50 cc. of water; then filtered and concentrated to 60 C. under 1 mm. Hg. The concentrated product consisted of 7.0 grams (87% yield) of 2-methyl-2-(O-ethyl ethylphosphonodithiomethylene)-l,3-dithiolane having an index of refraction N =1.5458 and analysis of 11.7% P and 33.9% S as compared to 10.2% P and 42.4% S, theoretical.

The following compounds were prepared by a procedure substantially in accordance with Example 1.

EXAMPLE 2 can s s-oH.

i s-cmo cm c.1150 s-o1r2 2 methyl 2 (O ethyl ethylphosphonodithiomethylene)- 1,3-oxathiolane; having an index of refraction N =1.5520, and analysis of 10.8% P and 33.5% S as compared to 10.8% P and 32.1% S, theoretical.

2 methyl 2 (O ethyl phenylphosphonodithiomethylene))-1,3-dithiolane; having an analysis of 9.1% P and 31.5% S as compared to 8.9% P and 36.5% S, theoretical.

EXAMPLE 4 CH3 s SCH2 iSCH2CCHa oinso s-cm 2 methyl 2 (O ethyl methylphosphonodithiomethylene)-1,3-dithiolane; having an index of refraction N =1.5899, and an analysis of 10.4% P and 41.0% S as compared to 10.7% P and 44.4% S, theoretical.

2 methyl 2 (O ethyl methylphosphonodithiomethylene)-1,3-oxathiolane; having an index of refraction N =1.5571, and an analysis of 11.3% P and 33.4% S as compared to 11.4% P and 35.0% S, theoretical.

The novel phosphonated aldehyde or ketone intermediates useful in the preparation of the novel pesticides of the invention may be represented by the general formula wherein alkylene, R, R, R and X are the same as defined hereinbefore for the novel pesticides.

The general process for preparing the novel intermediates of the invention may be illustrated by the following reaction:

wherein halo means a halogen radical such as chlorine, bromine or iodine; Y means an alkali metal to include for example, sodium and potassium; and all of the other substituents are the same as defined hereinbefore. Reaction temperatures, while they need not be critically controlled during these mildly exothermic reactions are normally maintained between about 0 C. and 100 C., preferably between C. and 50 C. Normally the reaction 4 will yield between 75% and 97.5% of the theoretical predicted amount of phosphonated intermediate.

EXAMPLE 6 To 21.2 grams of sodium and 700 ml. ethanol contained in a reactor flask fitted with a thermometer and stirring rod, while the temperature was maintained between C. and C., was added hydrogen sulfide until the solution was acidic to phenolphthalein. While maintaining the temperature of the reactants at 25 C., 50.0 grams of ethyl phosphonodichloridothionate was added dropwise over a period of 25 minutes. After stirring for an additional 30 minutes at 25 C., the mixture was heated to C. and stirred for 30 minutes longer. Then, 28.0 grams of chloroacetone was added dropwise over a period of six minutes while maintaining the temperature of the mixture between 20 C. and 25 C. The mixture was stirred for 30 minutes at 25 C. and then stirred at reflux for one hour. After cooling and filtering, the mixture was concentrated to C. under 1 mm. Hg. The concentrated product consisted of 51.7 grams yield) of O-ethyl- S (2 oxopropyl 1)-ethylphosphonodithioate having an index of refraction N 1.5309 and analysis of 12.7% P and 28.6% 5 compared to 13.7% P and 28.3% S, theoretical.

The following specific compounds were prepared by a procedure substantially in accordance with that of Example 1:

EXAMPLE 7 O ethyl S-(2 oxo-propyl-l)-phenylphosphonodithioate having an index of refraction N =1.5865, and analysis of 11.7% P and 23.9% S as compared to 11.3% P and 23.3% S, theoretical.

EXAMPLE 8 O ethyl S (2-oxo-propyl-1)-methylphosphonodithioate having an index of refraction N =l.5360, and analysis of 14.1% P and 30.1% S as compared to 14.6% P and 30.2% S, theoretical.

Although the new phosphonated cyclic mercaptals have been found to be generally active as pesticides, their miticidal activity, especially with the two-spotted mite, T erranychus telarius, is unexpectedly high. Insecticidal activity for the phosphonated cyclic mercaptals is illustrated in Table I wherein the percentage kill among the pest species is reported for a specified quantity of candidate compound, expressed in micrograms (,rg, herein termed the bioassay test), or for a percentage concentration in aqueous dispersion (hereinafter termed the screening test). A slanted line is used to separate the percentage kill for the pest species shown on the left from the percentage concentration (screening) or total quantity (bioassay) shown on the right.

Insect pest species HousefiyMusca domestica (Linn) American cockroachPeriplaneta amerl'cmm (Linn) German cockroach Blatella germanica (Linn) Spotted milkweed bug0ncopeltus fasciatus (Dallas) Mite test species Two-spotted mite--Tetranychus :telarius (Linn) TABLE I.MORTALITY OF REPRESENTATIVE SPECIES OF COMMON INSECT ORDERS AND MITES T. telarz'us M. P. ameri- B. ger- 0. fas- Post Systemic, domestt'ca cam manica ciatus embryonic Nymphs Eggs p.p.m.

Compound: 1

1 Example number, see supra.

In the screening tests for the insect species of Table I, from ten to twenty-five insects were caged in cardboard mailing tubes 3% in diameter and 2%" tall. The cages were supplied with cellophane bottoms and screen tops. Food and water were supplied to each cage. Dispersions of the test compounds were prepared by dissolving onehalf gram of the toxic material in ml. of acetone. This solution was then diluted with water containing 0.0175% v./v. Sponto 221, and emulsifying agent, the amount of water being sufficient to dilute the active ingredients to a concentration of 0.1% or below. The test insects were then sprayed with this dispersion. After twenty-four and seventy-two hours, counts were made to determine living and dead insects.

Some of the compounds which showed high mortality on house flies in the screening test were bioassayed on M. domestica. In this test, a known quantity of the toxicant was placed in a confined area. The same cages were employed as for the fly screening test. A weighed amount of the toxicant was placed in Pyrex petri dishes having a surface area of 18.8 sq. centimeters along with 1 ml. of acetone. After the solvent was evaporated by air-drying, a cage containing groups of twenty-five female flies, three to five days old, was placed over the residue. Counts of living and dead insects were made forty-eight hours after initiation of the test.

It has been further found that the compounds of the present invention are excellent systemic miticides. In testing for systemic action, pinto bean plants were placed in bottles containing 200ml. of the test solution and were held in place with cotton plugs. Only the roots were immersed. The solutions were prepared by dissolving the candidate miticide in acetone or other suitable solvent and then diluting with tap water. The final acetone concentration of the solution was never allowed to exceed 1% and the toxicant was initially tested at a concentration of 100 p.p.m. As soon as the plants were placed in the solution, they were infested with mites. Mortalities of post embryonic, nymph and ovicidal forms were determined seven days after initiation of the test.

Although the above tests were accomplished with aqueous dispersions, the toxic compounds can also be used ders, vapors, and dusts as best suited to the conditions of use. In many applications, fillers will be incorporated with the toxic compounds. For more specialized applications, the material may even be used in its pure, undiluted form.

When used herein the term pest is intended in the restricted sense generally recognized in the art as applying to the lower forms of life customarily controlled by chemical means and excluding the higher animals, the vertebrates, for example, rodents, birds, and larger forms which are more commonly controlled by mechanical means such as traps. It will be apparent to one skilled in the art that the toxic activity demonstrated hereinbefore on various test species is indicative of activity with species and orders not specifically shown.

The foregoing description is given by clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

I claim:

1. 2 methyl-Z-(O-ethyl ethylphosphonodithiomethylene)-l,3-oxathiolane.

References Cited UNITED STATES PATENTS 3,317,561 5/1967 Levy et al 260327 2,701,253 2/1955 Jones et al. 260-327 2,881,201 4/ 1959 Schrader 26046l 2,907,787 10/1959 Hoffman et a1. 260--46l 3,247,223 4/ 1966 Walsh et a1 260327 FOREIGN PATENTS 167,432 1/ 1951 Austria. 1,050,768 2/1959 Germany.

OTHER REFERENCES Djerassi et al.: Jour. Amer. Chem. Soc., vol. (1953 pp. 3704-8.

JAMES A. PATTEN, Primary Examiner US. Cl. X.R. 260-3409, 946; 424202 (2);? UNITED STATE. PATENT OFFICE CERTIFICATE OF CORRECT Patent No. 3,564,013 Da e February 16, 1971 hv fl Edward Nelson Walsh It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column 3, between lines 5 and 10 in Example 2,

the portion of the structural formula reading n S CH u 2 -CH C -CH should read O CH 2 -CH C CH l Column 3, between lines 50 and 54, in Example 5 the portion of the structural formula reading i should read R R O P-S R 0 Column 4, between lines 5 and 10, in Example 6, the structural formula reading II C H II 6 P-s-cH c-c11 C H O 2 5 should read S o C H u u 2 P-S-CH c-cn mg I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,564,013 Dated February 16, 1971 Patent No.

Edward Nelson Walsh PAGE 2 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[- 7 Column 4, between lines 35 and 40, in Example 7 the portion of the structural formula reading Column 6, line 29, the word "by" should read ---for---.

Signed and sealed this Lpth day of January 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSGHALK Attesting Officer Acting Commissioner of Pat 

